Peroxide-modified linear low density polyethylene films, sheets, and multilayer structures

ABSTRACT

The present disclosure provides a peroxide-modified polyethylene and related compositions as well as films, sheets, and multilayer structures made therefrom. A film composition is made from or containing a peroxide-modified polyethylene composition made from or containing a peroxide-modified polyethylene made from or containing the reaction products of a polyethylene composition made from or containing a first Ziegler-Natta-catalyzed polyethylene and a first amount of an organic peroxide to the second reactor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the Non-Provisional Patent Application, which claimsbenefit of priority to U.S. Provisional Application No. 62/451,652,filed Jan. 27, 2017, the contents of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

In general, the present disclosure relates to the field of chemistry.More specifically, the present disclosure relates to polymer chemistry.In particular, the present disclosure relates to peroxide-modifiedpolyethylene and related compositions as well as films, sheets, andmultilayer structures made therefrom.

BACKGROUND OF THE INVENTION

Ziegler-Natta (Z-N) catalyst systems can be used to produce linear lowdensity polyethylene (LLDPE), medium density polyethylene (MDPE), andhigh density polyethylene (HDPE) resins. However, some Z-N-catalyzedpolymers with high tear and impact strength have shown limitedusefulness for film and sheet applications because the polymers can havepoor extrudability.

An example is superhexene linear low density polyethylenes, which haveshown excellent tear and impact strength properties with poorextrudability.

Additionally, chromium-catalyzed LLDPE, MDPE, and HDPE products havedemonstrated good extrudability but poor tear and impact strengthproperties for film applications.

It is desirable to produce Z-N catalyzed polymers that provide good tearand impact strength properties while demonstrating extrudability similarto that of chromium-catalyzed polymers.

BRIEF SUMMARY OF THE INVENTION

In a general embodiment, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor;    -   (B) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a second reactor;    -   (C) admixing a first amount of an organic peroxide to the second        reactor;    -   (D) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene, thereby coupling the        polyethylene components and forming the peroxide-modified        polyethylene; and    -   (E) collecting the peroxide-modified polyethylene.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor;    -   (B) preparing a high density polyethylene in a second reactor;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the high density polyethylene from the second        reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the high density        polyethylene, thereby coupling the polyethylene components and        forming the peroxide-modified polyethylene; and    -   (G) collecting the peroxide-modified polyethylene.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor, having a melt index (ASTM D 1238) in the range of        about 5.5 g/10 min to about 7.5 g/10 min;    -   (B) preparing a second Ziegler-Natta-catalyzed polyethylene in a        second reactor, having a melt index in the range of about 0.5        g/10 min to about 3.0 g/10 min;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the second Ziegler-Natta-catalyzed polyethylene        from the second reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the second        Ziegler-Natta-catalyzed polyethylene, thereby coupling the        polyethylene components and forming a peroxide-modified        polyethylene; and    -   (E) collecting the peroxide-modified polyethylene.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor, having a melt index (ASTM D 1238) in the range of        about 0.5 g/10 min to about 160 g/10 min;    -   (B) preparing a second Ziegler-Natta-catalyzed polyethylene in a        second reactor, having a melt index in the range of about 0.5        g/10 min to about 7.0 g/10 min;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the second Ziegler-Natta-catalyzed polyethylene        from the second reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the second        Ziegler-Natta-catalyzed polyethylene, thereby coupling the        polyethylene components and forming a peroxide-modified        polyethylene; and    -   (E) collecting the peroxide-modified polyethylene.

In a general embodiment, the present disclosure provides aperoxide-modified polyethylene composition made from or containing aperoxide-modified polyethylene.

In a general embodiment, the present disclosure provides a filmcomposition made from or containing a peroxide-modified polyethylene.

In a general embodiment, the present disclosure provides a film madefrom or containing a layer made from or containing a peroxide-modifiedpolyethylene.

In a general embodiment, the process for preparing a peroxide-modifiedpolyethylene is extended to modification of polyethylene polymersprepared with catalysts other than Ziegler-Natta catalysts.

While multiple embodiments are disclosed, still other embodiments willbecome apparent to those skilled in the art from the following detaileddescription. As will be apparent, certain embodiments, as disclosedherein, are capable of modifications in various obvious aspects, allwithout departing from the spirit and scope of the claims as presentedherein. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following figures illustrate preferred embodiments of the subjectmatter disclosed herein. The claimed subject matter may be understood byreference to the following description taken in conjunction with theaccompanying figures, in which like reference numerals identify likeelements, and in which:

FIG. 1 shows gel permeation chromatographs for (a) a comparativechromium-catalyzed linear low density polyethylene, (b) a Ziegler-Nattacatalyzed linear low density polyethylene, and (c) a peroxide-modified,Ziegler-Natta catalyzed linear low density polyethylene.

FIG. 2 show graphs of head pressure measured in pounds per square inch(PSI) and screw speed measured in revolutions per minute (RPM) for (a) acomparative chromium-catalyzed linear low density polyethylene, (b) apolyethylene composition made from or containing 80 weight percent of aZiegler-Natta catalyzed linear low density polyethylene and 20 weightpercent of a comparative chromium-catalyzed linear low densitypolyethylene, based upon the total weight of the polyethylenecomposition, and (c) a peroxide-modified, Ziegler-Natta catalyzed linearlow density polyethylene.

FIG. 3 shows a peroxide curing profile for (a) a comparativechromium-catalyzed linear low density polyethylene without peroxide, (b)a comparative chromium-catalyzed linear low density polyethylene with1000 ppm peroxide, and (c) a peroxide-modified, Ziegler-Natta catalyzedlinear low density polyethylene with 1000 ppm peroxide.

FIG. 4 shows gel permeation chromatographs for (a) a comparativechromium-catalyzed linear low density polyethylene and (b) aperoxide-modified polyethylene prepared from a polyethylene compositionmade from or containing 20 weight percent of a firstZiegler-Natta-catalyzed polyethylene, having a melt index (ASTM D 1238)in the range of about 5.5 g/10 min to about 7.5 g/10 min, and 80 weightpercent of a second Ziegler-Natta-catalyzed polyethylene, having a meltindex in the range of about 0.5 g/10 min to about 3.0 g/10 min, basedupon the total weight of the polyethylene composition.

FIG. 5 shows a rheology plot for (a) a comparative superhexene, linearlow density polyethylene, having a melt index of 0.6 g/10 min and adensity of 0.9215 g/cc; (b) a comparative chromium-catalyzed linear lowdensity polyethylene, having a melt index of 0.75 g/10 min and a densityof 0.920 g/cc; (c) a peroxide-modified polyethylene prepared from apolyethylene composition made from or containing 20 weight percent of afirst Ziegler-Natta-catalyzed polyethylene, having a melt index (ASTM D1238) in the range of about 5.5 g/10 min to about 7.5 g/10 min, and 80weight percent of a second Ziegler-Natta-catalyzed polyethylene, havinga melt index in the range of about 0.5 g/10 min to about 3.0 g/10 min,based upon the total weight of the polyethylene composition; and (d) aperoxide-modified polyethylene prepared from a polyethylene compositionmade from or containing 10 weight percent of a firstZiegler-Natta-catalyzed polyethylene, having a melt index (ASTM D 1238)in the range of about 5.5 g/10 min to about 7.5 g/10 min, and 90 weightpercent of a second Ziegler-Natta-catalyzed polyethylene, having a meltindex in the range of about 0.5 g/10 min to about 3.0 g/10 min, basedupon the total weight of the polyethylene composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter.However, this invention can be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. As such, it will be apparent tothose skilled in the art that the embodiments can incorporate changesand modifications without departing from the general scope. It isintended to include all the modifications and alterations in so far asthe modifications and alterations come within the scope of the appendedclaims or the equivalents thereof.

As used in this specification and the claims, the singular forms “a,”“an,” and “the” include plural referents unless the context clearlydictates otherwise.

As used in this specification and the claims, the terms “comprising,”“containing,” or “including” mean that at least the named compound,element, material, particle, or method step, etc., is present in thecomposition, the article, or the method, but does not exclude thepresence of other compounds, elements, materials, particles, or methodsteps, etc., even if the other such compounds, elements, materials,particles, or method steps, etc., have the same function as that whichis named, unless expressly excluded in the claims. It is also to beunderstood that the mention of one or more method steps does notpreclude the presence of additional method steps before or after thecombined recited steps or intervening method steps between those stepsexpressly identified.

Moreover, it is also to be understood that the lettering of processsteps or ingredients is a means for identifying discrete activities oringredients and the recited lettering can be arranged in any sequence,unless expressly indicated.

For the purpose of the present description and of the claims whichfollow, except where otherwise indicated, numbers expressing amounts,quantities, percentages, and so forth, are to be understood as beingmodified by the term “about”. Also, ranges include any combination ofthe maximum and minimum points disclosed and include any intermediateranges therein, which may or may not be specifically enumerated herein.

Definitions

In the present description, the term “chromium catalyst” can refer to CrUCAT-B.

In the present description, the term “chromium-catalyzed polymer” meanany polymer that is made in the presence of a chromium catalyst.

In the present description, the term “film” refers to structures havinga thickness of less than about 10 mils. A “sheet” has a thickness of asleast about 10 mils. Multilayer films or sheets have at least twolayers. In some embodiments, at least one layer serves as a barrierlayer.

In the present description, the term “first” refers to the order inwhich a particular species is presented and does not necessarilyindicate that a “second” species will be presented. For example, “firstpolymer composition” refers to the first of at least one polymercomposition. The term does not reflect priority, importance, orsignificance in any other way. Similar terms used that can be usedherein include “second,” “third,” “fourth,” etc.

In the present description, the term “high density polyethylene” refersto ethylene based polymers having a density of from about 0.94 g/cc toabout 0.97 g/cc.

In the present description, the term “low density polyethylene” refersto ethylene based polymers having a density in a range of 0.88 g/cc to0.925 g/cc. In the present description, the term “linear low densitypolyethylene” refers to substantially linear low density polyethylenecharacterized by the absence of long chain branching.

In the present description, the term “medium density polyethylene”refers to ethylene based polymers having a density of from 0.92 g/cc to0.94 g/cc.

In the present description, the terms “monomer” and “comonomer” are usedinterchangeably. The terms mean any compound with a polymerizable moietythat is added to a reactor in order to produce a polymer. In thoseinstances in which a polymer is described as comprising one or moremonomers, e.g., a polymer comprising propylene and ethylene, thepolymer, of course, comprises units derived from the monomers, e.g.,—CH₂—CH₂—, and not the monomer itself, e.g., CH₂═CH₂.

In the present description, the term “polymer” means a macromolecularcompound prepared by polymerizing monomers of the same or differenttype. The term “polymer” includes homopolymers, copolymers, terpolymers,interpolymers, and so on.

In the present description, the term “polymer composition” refers to acomposition made from or containing at least one polymer.

In the present description, the term “Ziegler-Natta catalyst” can referto (i) UCAT-A, (ii) UCAT-J, or (iii) a catalyst including MRx, wherein Mis a transition metal, R is a halogen, an alkoxy, or a hydrocarboxylgroup and x is the valence of the transition metal.

In the present description, the terms “Ziegler-Natta-catalyzed polymer”and “Z-N-catalyzed polymer” mean any polymer that is made in thepresence of a Ziegler-Natta catalyst.

Testing

ASTM D 638 is entitled “Standard Test Method for Tensile Properties ofPlastics.” The term “ASTM D 638” as used herein refers to the testmethod designed to produce tensile property data for the control andspecification of plastic materials. This test method covers thedetermination of the tensile properties of unreinforced and reinforcedplastics in the form of standard dumbbell-shaped test specimens whentested under defined conditions of pretreatment, temperature, humidity,and testing machine speed. This test method can be used for testingmaterials of any thickness up to 14 mm (0.55 in.). This test method wasapproved in 2010, the contents of which are incorporated herein byreference in its entirety.

ASTM D 648 is entitled “Standard Test Method for Deflection Temperatureof Plastics under Flexural Load in the Edgewise Position.” The term“ASTM D 648” as used herein refers to the test method determination ofthe temperature at which an arbitrary deformation occurs when specimensare subjected to an arbitrary set of testing conditions. This testmethod applies to molded and sheet materials available in thicknesses of3 mm [⅛ in.] or greater and which are rigid or semirigid at normaltemperature. This test method was approved in 2007, the contents ofwhich are incorporated herein by reference in its entirety.

ASTM D 792 is entitled “Test Methods for Density and Specific Gravity(Relative Density) of Plastics by Displacement.” The term “ASTM D 792”as used herein refers to the standard test method for determining thespecific gravity (relative density) and density of solid plastics informs such as sheets, rods, tubes, or molded items. The test methodincludes determining the mass of a specimen of the solid plastic in air,determining the apparent mass of the specimen upon immersion in aliquid, and calculating the specimen's specific gravity (relativedensity). This test method was approved on Jun. 15, 2008 and publishedJuly 2008, the contents of which are incorporated herein by reference inits entirety.

ASTM D 1238 is entitled “Test Method for Melt Flow Rates ofThermoplastics by Extrusion Plastometer.” The term “ASTM D 1238” as usedherein refers to a test method covering the determination of the rate ofextrusion of molten thermoplastic resins using an extrusion plastometer.After a specified preheating time, resin is extruded through a die witha specified length and orifice diameter under prescribed conditions oftemperature, load, and piston position in the barrel. This test methodwas approved on Feb. 1, 2012 and published March 2012, the contents ofwhich are incorporated herein by reference in its entirety.

Throughout the present description and claims, the standard melt indexvalues of polyethylene polymers are measured according to ASTM D 1238,using a piston load of 2.16 kg and at a temperature of 190 degreesCelsius. The High Load Melt Index (or HLMI) values are also measuredaccording to ASTM D 1238, but using a piston load of 21.6 kg and at atemperature of 190 degrees Celsius.

ASTM D 1505 is entitled “Standard Test Method for Density of Plastics bythe Density-Gradient Technique.” The term “ASTM D 1505” as used hereinrefers to a test method based on observing the level to which a testspecimen sinks in a liquid column exhibiting a density gradient, incomparison with standards of known density. This test method wasapproved on Jul. 1, 2010 and published September 2010, the contents ofwhich are incorporated herein by reference in its entirety.

For the referenced ASTM standards, visit the ASTM website, www.astm.org,or contact ASTM Customer Service at service@astm.org.

“Molecular Weight Distribution (Mw/Mn)” is measured by gel permeationchromatography. MWD and the ratio M_(w)/M_(n) are determined using aWaters 150-C ALC/Gel Permeation Chromatography (GPC) system equippedwith a TSK column set (type GMHXL-HT) working at 135 degrees Celsiuswith 1,2-dichlorobenzene as solvent (ODCB) (stabilized with 0.1 volumeof 2,6-di-t-butyl p-cresole (BHT)) at flow rate of 1 ml/min. The sampleis dissolved in ODCB by stirring continuously at a temperature of 140degrees Celsius for 1 hour. The solution is filtered through a 0.45 μmTeflon membrane. The filtrate (concentration 0.08-1.2 g/l injectionvolume 300 μl) is subjected to GPC. Monodisperse fractions ofpolystyrene (provided by Polymer Laboratories) are used as standard.

In general embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor, having a molecular weight distribution;    -   (B) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a second reactor;    -   (C) admixing a first amount of an organic peroxide to the second        reactor;    -   (D) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene, thereby modifying the        molecular weight distribution of the polyethylene components and        forming the peroxide-modified polyethylene; and    -   (E) collecting the peroxide-modified catalyzed polyethylene.

In some embodiments, Ziegler-Natta catalyst systems are formed from thecombination of a metal component with one or more additional components,such as a catalyst support, a co-catalyst and/or one or more electrondonors. In some embodiments, the metal component is an active catalystsite.

In some embodiments, a Ziegler-Natta catalyst includes a metal componentrepresented by the formula:

MR_(x)

wherein M is a transition metal, R is a halogen, an alkoxy, or ahydrocarboxyl group and x is the valence of the transition metal. Insome embodiments, x is from 1 to 4.

In some embodiments, the transition metal is selected from Groups IVthrough VIB. In some embodiments, the transition metal is selected fromthe group consisting of titanium, chromium, and vanadium.

In some embodiments, R is selected from the group consisting ofchlorine, bromine, carbonate, ester, and an alkoxy group.

In some embodiments, the catalyst components include TiCl₄, TiBr₄,Ti(OC₂H₅)₃Cl, Ti(OC₃H₇)₂Cl₂, Ti(OC₆H₁₃)₂Cl₂, Ti(OC₂H₅)₂Br₂ andTi(OC₁₂H₂₅)Cl₃.

In some embodiments, the catalyst is “activated”. In some embodiments,activation is accomplished by contacting the catalyst with an activator,which is also referred to in some instances as a “co-catalyst”. In someembodiments, Z-N activators include organoaluminum compounds, such astrimethyl aluminum (TMA), triethyl aluminum (TEAl) and triisobutylaluminum (TiBAl).

In some embodiments, the Ziegler-Natta catalyst system includes one ormore electron donors, such as internal electron donors and/or externalelectron donors. In some embodiments, internal electron donors areselected from the group consisting of amines, amides, esters, ketones,nitriles, ethers, thioethers, thioesters, aldehydes, alcoholates, salts,organic acids, phosphines, diethers, succinates, phthalates, malonates,maleic acid derivatives, dialkoxybenzenes, and combinations thereof.

In some embodiments, the internal donor includes a C₃-C₆ cyclic ether.In some embodiments, the internal donor includes a C₃-C₅ cyclic ether.In some embodiments, the cyclic ethers is selected from the groupconsisting of tetrahydrofurane, dioxane, methyltetrahydrofurane andcombinations thereof. In some embodiments, internal donors are asdisclosed in Patent Cooperation Treaty Publication No. WO2012/025379,which is incorporated by reference herein.

In some embodiments, the external electron donors are selected from thegroup consisting of monofunctional or polyfunctional carboxylic acids,carboxylic anhydrides, carboxylic esters, ketones, ethers, alcohols,lactones, organophosphorus compounds, and organosilicon compounds. Insome embodiments, the external donor is selected from the groupconsisting of diphenyldimethoxysilane (DPMS),cyclohexylmethyldimethoxysilane (CMDS), diisopropyldimethoxysilane(DIDS), and dicyclopentyldimethoxysilane (CPDS). In some embodiments,the external donor is the same as or different from the internalelectron donor used. In some embodiments, the catalyst system is free ofan external donor.

In some embodiments, the components of the Ziegler-Natta catalyst systemare associated with a support, either in combination with each other orseparate from one another. In some embodiments, the components of theZiegler-Natta catalyst system are not associated with a support. In someembodiments, the Z-N support materials includes a magnesium dihalide orsilica. In some embodiments, the magnesium dihalide is magnesiumdichloride or magnesium dibromide.

In some embodiments, the support includes a magnesium compoundrepresented by the formula:

MgCl₂(R″OH)_(m)

wherein R″ is a C₁-C₁₀ alkyl and m is in a range of 0.5 to 3.

In some embodiments, the Ziegler-Natta catalyst system exhibits a molarratio of support to metal component (measured as the amount of metal ofeach component) Mg:Ti of greater than about 5:1, alternatively in arange of about 7:1 to about 50:1, alternatively in a range of about 10:1to about 25:1.

In some embodiments, the Ziegler-Natta catalyst system exhibits a molarratio of support to internal donor Mg:ID of less than about 3:1,alternatively less than about 2.9:1, alternatively less than about2.6:1, alternatively less than about 2.1:1, alternatively less thanabout 2:1, alternatively from about 1.1:1 to about 1.4:1.

In some embodiments, the Ziegler-Natta catalyst system exhibits an X-raydiffraction spectrum in which the range of 2θ diffraction angles between5.0° and 20.0°, at least three main diffraction peaks are present atdiffraction angles 2θ of about 7.2±0.2°, about 11.5±0.2°, and about14.5±0.2°, the peak at 2θ of about 7.2±0.2° being the most intense peakand the peak at about 11.5±0.2° having an intensity less than about 0.9times the intensity of the most intense peak.

In some embodiments, the intensity of the peak at 11.5° has an intensityless than about 0.8 times the intensity of the diffraction peak at 2θdiffraction angles of about 7.2±0.2°. In some embodiments, the intensityof the peak at about 14.5±0.2° is less than about 0.5 times,alternatively less than about 0.4 times the intensity of the diffractionpeak at 2θ diffraction angles of about 7.2±0.2°.

In some embodiments, another diffraction peak is present at diffractionangles 2θ of about 8.2±0.2° having an intensity equal to or lower thanthe intensity of the diffraction peak at 2θ diffraction angles of about7.2±0.2°. In some embodiments, the intensity of the peak at diffractionangles 2θ of about 8.2±0.2° is less than about 0.9, alternatively lessthan about 0.5 times the intensity of the diffraction peak at 2θdiffraction angles of about 7.2±0.2°.

In some embodiments, an additional broad peak is observed at diffractionangles 2θ of about 18.2±0.2° having an intensity less than about 0.5times the intensity of the diffraction peak at 2θ diffraction angles ofabout 7.2±0.2°. As referenced herein, the X-ray diffraction spectra arecollected by using Bruker D8 advance powder diffractometer or acomparable apparatus.

The Ziegler-Natta catalyst may be formed by many methods. In someembodiments, the Ziegler-Natta catalyst is formed by contacting atransition metal halide with a metal alkyl or metal hydride. In someembodiments, the Ziegler-Natta catalyst is prepared as described in atleast one of U.S. Pat. Nos. 4,298,718; 4,298,718; 4,544,717; 4,767,735;and 4,544,717, which are incorporated by reference herein.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene is alinear low density polyethylene, a medium density polyethylene, or ahigh density polyethylene.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene is alinear low density polyethylene, having a melt index (ASTM D 1238) inthe range of about 5.5 g/10 min to about 7.5 g/10 min, a density (ASTM D1505) in the range of about 0.88 g/cc to about 0.925 g/cc, a tensilestrength (ASTM D 638) in the range of about 1400 psi to about 2,000 psi,and an elongation at break (ASTM D 638) in the range of about 750% toabout 1000%. In some embodiments, the melt index of the linear lowdensity polyethylene is 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3,6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5 g/10 min, oran intermediate melt index. In some embodiments, the density is 0.88,0.89, 0.90, 0.91, 0.92, 0.925 g/cc, or an intermediate density. In someembodiments, the tensile strength is 1400, 1450, 1500, 1550, 1600, 1650,1700, 1750, 1800, 1850, 1900, 1950, 2,000 psi, or an intermediatetensile strength. In some embodiments, the elongation at break is 750,800, 850, 900, 950, 1000%, or an intermediate elongation at break.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene hasa first molecular weight distribution, the peroxide-modifiedpolyethylene has a second molecular weight distribution, and the firstmolecular weight distribution and the second molecular weightdistribution are dissimilar.

In some embodiments, the organic peroxide is added in a first amountless than about 2000 ppm. In other embodiments, the organic peroxide isadded in a first amount less than about 1500 ppm. In yet otherembodiments, the organic peroxide is added in an amount in the range ofabout 100 ppm to about 700 ppm. In further embodiments, the organicperoxide is added in a first amount of about 100, 200, 300, 400, 500,600, 700 ppm, or an intermediate amount.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor;    -   (B) preparing a high density polyethylene in a second reactor;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the high density polyethylene from the second        reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the high density        polyethylene, thereby coupling the polyethylene components and        forming the peroxide-modified polyethylene; and    -   (G) collecting the peroxide-modified polyethylene.

Alternatively and for consistency with the general embodiment, thisembodiment can be described as the general embodiment further includingthe steps of:

-   -   (A2) preparing a high density polyethylene in a third reactor;    -   (B2) transferring the high density polyethylene from the third        reactor to the second reactor,    -   wherein the polyethylene composition is made from or further        contains the high density polyethylene.

In some embodiments, the high density polyethylene has a melt index(ASTM D 1238) in the range of about 0.1 g/10 min to about 1.5 g/10 min,a density (ASTM D 1505) in the range of about 0.94 g/cc to about 0.97g/cc, a tensile strength (ASTM D 638) in the range of about 2,500 psi toabout 3,500 psi, and an elongation at break (ASTM D 638) in the range ofabout 600% to about 1000%. In some embodiments, the melt index is about0.5 g/10 min to about 1.0 g/10 min, alternatively 0.5, 0.6, 0.7, 0.8,0.9, 1.0 g/10 min, or an intermediate melt index. In some embodiments,the density is 0.940, 0.945, 0.950, 0.955, 0.960, 0.965, 0.970 g/cc, oran intermediate density. In some embodiments, the tensile strength is inthe range of about 3,000 psi to about 3,500 psi, alternatively, 3,000,3,100, 3,200, 3,300, 3,400, 3,500 psi, or an intermediate tensilestrength. In some embodiments, the elongation at break is 600, 650, 700,750, 800, 850, 900, 950, 1000%, or an intermediate elongation at break.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene hasa first molecular weight distribution, the high density polyethylene hasa second molecular weight distribution, the peroxide-modifiedpolyethylene has a third molecular weight distribution, and the thirdmolecular weight distribution differs from either the first molecularweight distribution or the second molecular weight distribution.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene isadded to the third reactor in an amount from about 60 weight percent toabout 95 weight percent, based upon the total weight of the polyethylenecomposition, and the high density polyethylene is added in an amountfrom about 5 weight percent to about 40 weight percent, based upon thetotal weight of the polyethylene composition. In some embodiments, thefirst Ziegler-Natta-catalyzed polyethylene is added in amount from about75 weight percent to about 90 weight percent, alternatively 75, 76, 77,78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 wt %, or anintermediate weight percent. In some embodiments, the high densitypolyethylene is added in an amount from about 15 weight percent to about25 weight percent, alternatively 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, 25 wt %, or an intermediate weight percent.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor, having a melt index (ASTM D 1238) in the range of        about 5.5 g/10 min to about 7.5 g/10 min and;    -   (B) preparing a second Ziegler-Natta-catalyzed polyethylene in a        second reactor, having a melt index in the range of about 0.5        g/10 min to about 3.0 g/10 min;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the second Ziegler-Natta-catalyzed polyethylene        from the second reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the second        Ziegler-Natta-catalyzed polyethylene, thereby coupling the        polyethylene components and forming a peroxide-modified        polyethylene; and    -   (E) collecting the peroxide-modified polyethylene.

Alternatively and for consistency with the general embodiment, thisembodiment can be described as the general embodiment further includingthe steps of:

-   -   (A2) preparing a second Ziegler-Natta-catalyzed polyethylene in        a third reactor;    -   (B2) transferring the second Ziegler-Natta-catalyzed        polyethylene from the third reactor to the second reactor,    -   wherein    -   (i) the first Ziegler-Natta-catalyzed polyethylene has a melt        index (ASTM D 1238) in the range of about 5.5 g/10 min to about        7.5 g/10 min;    -   (ii) the second Ziegler-Natta-catalyzed polyethylene has a melt        index in the range of about 0.5 g/10 min to about 3.0 g/10 min;        and    -   (iii) the polyethylene composition is made from or further        contains the second Ziegler-Natta-catalyzed polyethylene.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene is alinear low density polyethylene, having a density (ASTM D 1505) in therange of about 0.88 g/cc to about 0.925 g/cc, a tensile strength (ASTM D638) in the range of about 1400 psi to about 2,000 psi, and anelongation at break (ASTM D 638) in the range of about 750% to about1000%. In some embodiments, the melt index of the linear low densitypolyethylene is 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5,6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5 g/10 min, or anintermediate melt index. In some embodiments, the density is 0.88, 0.89,0.90, 0.91, 0.92, 0.925 g/cc, or an intermediate density. In someembodiments, the tensile strength is 1400, 1450, 1500, 1550, 1600, 1650,1700, 1750, 1800, 1850, 1900, 1950, 2,000 psi, or an intermediatetensile strength. In some embodiments, the elongation at break is 750,800, 850, 900, 950, 1000%, or an intermediate elongation at break.

In some embodiments, the second Ziegler-Natta-catalyzed polyethylene isa linear low density polyethylene, having a melt index (ASTM D 1238) inthe range of about 1.5 g/10 min to about 2.5 g/10 min and a density(ASTM D 1505) in the range of about 0.88 g/cc to about 0.925 g/cc. Insome embodiments, the melt index of the linear low density polyethyleneis 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5 g/10 min, oran intermediate melt index. In some embodiments, the density is 0.88,0.89, 0.90, 0.91, 0.92, 0.925 g/cc, or an intermediate density.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene hasa first molecular weight distribution, the secondZiegler-Natta-catalyzed polyethylene has a second molecular weightdistribution, the peroxide-modified polyethylene has a third molecularweight distribution, and the third molecular weight distribution differsfrom either the first molecular weight distribution or the secondmolecular weight distribution. In some embodiments, theperoxide-modified polyethylene has a molecular weight distribution of atleast two modes.

In some embodiments, the first Ziegler-Natta-catalyzed polyethylene isadded to the third reactor in an amount from about 5 weight percent toabout 30 weight percent, based upon the total weight of the polyethylenecomposition, and the second Ziegler-Natta-catalyzed polyethylene isadded in an amount from about 70 weight percent to about 95 weightpercent, based upon the total weight of the polyethylene composition. Insome embodiments, the first Ziegler-Natta-catalyzed polyethylene isadded in amount from about 10 weight percent to about 20 weight percent,alternatively 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 wt %, or anintermediate weight percent. In some embodiments, the secondZiegler-Natta-catalyzed polyethylene is added in an amount from about 80weight percent to about 90 weight percent, alternatively 80, 81, 82, 83,84, 85, 86, 87, 88, 89, 90 wt %, or an intermediate weight percent.

In some embodiments, the present disclosure provides a process forpreparing a peroxide-modified polyethylene including the steps of:

-   -   (A) preparing a first Ziegler-Natta-catalyzed polyethylene in a        first reactor, having a melt index (ASTM D 1238) in the range of        about 0.5 g/10 min to about 160 g/10 min;    -   (B) preparing a second Ziegler-Natta-catalyzed polyethylene in a        second reactor, having a melt index in the range of about 0.5        g/10 min to about 7.0 g/10 min;    -   (C) transferring the first Ziegler-Natta-catalyzed polyethylene        from the first reactor to a third reactor;    -   (D) transferring the second Ziegler-Natta-catalyzed polyethylene        from the second reactor to the third reactor;    -   (E) admixing a first amount of an organic peroxide to the third        reactor;    -   (F) reacting the organic peroxide with a polyethylene        composition made from or containing the first        Ziegler-Natta-catalyzed polyethylene and the second        Ziegler-Natta-catalyzed polyethylene, thereby coupling the        polyethylene components and forming a peroxide-modified        polyethylene; and    -   (E) collecting the peroxide-modified polyethylene.

Alternatively and for consistency with the general embodiment, thisembodiment can be described as the general embodiment further includingthe steps of:

-   -   (A2) preparing a second Ziegler-Natta-catalyzed polyethylene in        a third reactor;    -   (B2) transferring the second Ziegler-Natta-catalyzed        polyethylene from the third reactor to the second reactor,    -   wherein    -   (i) the first Ziegler-Natta-catalyzed polyethylene has a melt        index (ASTM D 1238) in the range of about 0.5 g/10 min to about        160 g/10 min;    -   (ii) the second Ziegler-Natta-catalyzed polyethylene has a melt        index in the range of about 0.5 g/10 min to about 7.0 g/10 min;        and    -   (iii) the polyethylene composition is made from or further        contains the second Ziegler-Natta-catalyzed polyethylene.

In a general embodiment, the present disclosure provides aperoxide-modified polyethylene composition made from or containing aperoxide-modified polyethylene. In some embodiments, theperoxide-modified polyethylene has a viscosity at 100 rad/s at 190° C.less than about 23,400 poise, alternatively less than about 22,000poise, alternatively less than about 21,000 poise.

In some embodiments, the peroxide-modified polyethylene composition isfurther made from or containing an additives composition. In someembodiments, the additives are selected from the group consisting ofcolorants, odorants, deodorants, plasticizers, impact modifiers,fillers, nucleating agents, lubricants, surfactants, wetting agents,flame retardants, ultraviolet light stabilizers, antioxidants, biocides,metal deactivating agents, thickening agents, heat stabilizers,defoaming agents, other coupling agents, polymer alloy compatibilizingagent, blowing agents, emulsifiers, crosslinking agents, waxes,particulates, flow promoters, and other materials added to enhanceprocessability or end-use properties of the polymeric components.

In a general embodiment, the present disclosure provides a filmcomposition made from or containing a peroxide-modified polyethylenecomposition.

In a general embodiment, the present disclosure provides a film madefrom or containing a layer made from or containing a film composition.In some embodiments, the film is a multi-layer film having more than onelayer.

In some embodiments, the film, based upon an 8.0 mil thickness, has adart drop greater than about 550 g, alternatively greater than about 750g, alternatively greater than about 1000 g. In some embodiments, thefilm, based upon an 8.0 mil thickness, has MD Modulus greater than about29,000 psi, alternatively greater than about 30,000 psi, alternativelygreater than about 32,500 psi, alternatively greater than about 33,500psi. In some embodiments, the film, based upon an 8.0 mil thickness, hasTD Modulus greater than about 29,000 psi, alternatively greater thanabout 30,000 psi, alternatively greater than about 32,500 psi,alternatively greater than about 33,500 psi. In some embodiments, thefilm, based upon an 8.0 mil thickness, has MD tear greater than about1,000 g, alternatively greater than about 2,000 g, alternatively greaterthan about 2,500 g. In some embodiments, the film, based upon an 8.0 milthickness, has TD tear greater than about 2,000 g, alternatively greaterthan about 3,000 g, alternatively greater than about 3,500 g.

In a general embodiment, the present disclosure provides a sheetcomposition made from or containing a peroxide-modified polyethylenecomposition.

In a general embodiment, the present disclosure provides a sheet madefrom or containing a layer made from or containing a sheet composition.In some embodiments, the sheet is a multi-layer sheet having more thanone layer.

Examples

The following examples are included to demonstrate embodiments. Itshould be appreciated by those of skill in the art that the techniquesdisclosed in the examples which follow represent techniques discoveredto function well, and thus can be considered to constitute exemplarymodes of practice. However, those of skill in the art should, in lightof the present disclosure, appreciate that many changes can be made inthe specific embodiments which are disclosed and still obtain a like orsimilar result without departing from the spirit and scope of thisdisclosure.

FIG. 1 shows that following peroxide modification, the Ziegler-Nattacatalyzed linear low density polyethylene achieved a molecular weightdistribution more similar to the chromium-catalyzed linear low densitypolyethylene.

Comparative Example 1 is a chromium-catalyzed linear low densitypolyethylene, having a melt index of 0.75 g/10 min and a density of0.920 g/cc. Comparative Example 2 is a Ziegler-Natta catalyzed linearlow density polyethylene, having a melt index of 2.0 g/10 min and adensity of 0.918 g/cc. Example 3 is a peroxide-modified Ziegler-Nattacatalyzed linear low density polyethylene, having a melt index of 0.96g/10 min.

FIG. 2 shows that following peroxide modification, the Ziegler-Nattacatalyzed linear low density polyethylene achieved a screw speedcomparable to the chromium-catalyzed polyethylene while demonstrating alower head pressure.

Comparative Example 4 is a polyethylene blend made from or containingabout 80 weight percent of a Ziegler-Natta catalyzed linear low densitypolyethylene, having a melt index of 2.0 g/10 min and a density of 0.917g/cc, and about 20 weight percent of a chromium-catalyzed linear lowdensity polyethylene having a melt index of 0.75 g/10 min and a densityof 0.920 g/cc, both weight percents based upon the total weight of thepolyethylene blend.

FIG. 3 shows that the peroxide-modified Ziegler-Natta catalyzed linearlow density polyethylene achieves a cure profile at a lower viscosityover the entire temperature range similar to that a comparablechromium-catalyzed polyethylene.

Example 5 is the peroxide-modified Ziegler-Natta catalyzed linear lowdensity polyethylene with an additional 1000 ppm of an organic peroxide.Comparative Example 6 is a chromium-catalyzed linear low densitypolyethylene with 1000 ppm of an organic peroxide.

FIG. 4 shows that following peroxide modification, a polyethylenecomposition made from or containing 20 weight percent of a firstZiegler-Natta-catalyzed polyethylene, having a melt index (ASTM D 1238)in the range of about 5.5 g/10 min to about 7.5 g/10 min, and 80 weightpercent of a second Ziegler-Natta-catalyzed polyethylene, having a meltindex in the range of about 0.5 g/10 min to about 3.0 g/10 min, basedupon the total weight of the polyethylene composition achieved amolecular weight distribution similar to the chromium-catalyzed linearlow density polyethylene.

Example 6 is the peroxide-modified polyethylene.

FIG. 5 shows that a peroxide-modified polyethylene prepared from apolyethylene composition made from or containing 20 weight percent of afirst Ziegler-Natta-catalyzed polyethylene, having a melt index (ASTM D1238) in the range of about 5.5 g/10 min to about 7.5 g/10 min, and 80weight percent of a second Ziegler-Natta-catalyzed polyethylene, havinga melt index in the range of about 0.5 g/10 min to about 3.0 g/10 min,based upon the total weight of the polyethylene composition, similarrheological properties as a chromium-catalyzed linear low densitypolyethylene, having a melt index of 0.75 g/10 min and a density of0.920 g/cc. The figure also shows a peroxide-modified polyethyleneprepared from a polyethylene composition made from or containing 10weight percent of a first Ziegler-Natta-catalyzed polyethylene, having amelt index (ASTM D 1238) in the range of about 5.5 g/10 min to about 7.5g/10 min, and 90 weight percent of a second Ziegler-Natta-catalyzedpolyethylene, having a melt index in the range of about 0.5 g/10 min toabout 3.0 g/10 min, based upon the total weight of the polyethylenecomposition, similar rheological properties as a chromium-catalyzedlinear low density polyethylene, having a melt index of 0.75 g/10 minand a density of 0.920 g/cc. The exemplified embodiments show lowerviscosity at high shear rates and higher viscosity at low shear ratesthan a superhexene, linear low density polyethylene, having a melt indexof 0.6 g/10 min and a density of 0.9215 g/cc.

For Examples 7 and 8 and Comparative Examples 9 and 10, variouscompounds were formulated to prepare the test specimen. The materialswere admixed in the weight percents shown in TABLE 1.

The first Ziegler-Natta-catalyzed, linear low density polyethylene had amelt index of 6.5 g/10 min and a density of 0.918 g/cc.

The second Ziegler-Natta-catalyzed, linear low density polyethylene hada melt index of 2.0 g/10 min and a density of 0.917 g/cc.

A comparative linear low density polyethylene (LLDPE-1) is asuperhexene, linear low density polyethylene, having a melt index of 0.6g/10 min and a density of 0.9215 g/cc.

A comparative linear low density polyethlene (LLDPE-2) is achromium-catalyzed linear low density polyethylene, having a melt indexof 0.75 g/10 min and a density of 0.920 g/cc.

An organic peroxide is diisopropylbenzene dihydroperoxide (DBDH).

TABLE 1 Components Example 7 Example 8 Comp. Ex. 9 Comp. Ex. 10 FirstZ-N polymer 10.0 20.0 Second Z-N 89.6 79.6 polymer LLDPE-1 99.6 LLDPE-299.6 Polymer 0.2 0.2 0.2 0.2 processing aid DBDH 0.2 0.2 0.2 0.2Physical Properties of an 8.0 mil thick film Dart Drop, g 1,030 1,0101,950 520 MD Mod, psi 34,000 34,200 28,800 32,400 TD Mod, psi 33,80035,300 28,800 33,400 MD Tear, g 2,849 2,951 4,805 965 TD Tear, g 3,8753,843 4,575 1,814

It should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of this disclosure as defined by the appended claims. Moreover,the scope of the present application is not intended to be limited tothe particular embodiments of the process, machine, manufacture,composition of matter, means, methods and steps described in thespecification. As one of the ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein can be utilized. Accordingly, the appended claims areintended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods, or steps.

What is claimed is:
 1. A film composition comprising: (a) aperoxide-modified polyethylene composition comprising (I) aperoxide-modified polyethylene comprising (A) the reaction products of(i) a polyethylene composition comprising a firstZiegler-Natta-catalyzed polyethylene and (ii) a first amount of anorganic peroxide to the second reactor.
 2. The film composition of claim1, wherein the polyethylene composition further comprises (i2) a highdensity polyethylene.
 3. The film composition of claim 1, wherein (i2)the polyethylene composition further comprises a secondZiegler-Natta-catalyzed polyethylene; (iii) the firstZiegler-Natta-catalyzed polyethylene has a melt index (ASTM D 1238) inthe range of about 5.5 g/10 min to about 7.5 g/10 min; and (iv) thesecond Ziegler-Natta-catalyzed polyethylene has a melt index in therange of about 0.5 g/10 min to about 3.0 g/10 min.
 4. The filmcomposition of claim 1, wherein (i2) the polyethylene compositionfurther comprises a second Ziegler-Natta-catalyzed polyethylene; (iii)the first Ziegler-Natta-catalyzed polyethylene has a melt index (ASTM D1238) in the range of about 0.5 g/10 min to about 160 g/10 min; and (iv)the second Ziegler-Natta-catalyzed polyethylene has a melt index in therange of about 0.5 g/10 min to about 7.0 g/10 min.
 5. A film comprising:(1) a layer comprising (a) a film composition comprising aperoxide-modified polyethylene composition.
 6. The film of claim 5,wherein, based upon an 8.0 mil thickness, the film has a dart dropgreater than about 550 g, a MD Modulus greater than about 29,000 psi, aTD Modulus greater than about 29,000 psi, a MD tear greater than about1,000 g, and a TD tear greater than about 2,000 g.
 7. The film of claim5, wherein the peroxide-modified polyethylene has a viscosity at 100rad/s at 190° C. less than about 23,400 poise.